Means for sharpening a circular knife



July 9, 1940. H. LLHASWELL 2,207,433

MEANS FOR SHARPENING A CIRCULAR KNIFE Filed March 14, 1958 2Sheets-Sheet 1 INVENTOR July 9, 1940. H. L. HASWELL 2,207,433

MEANS FOR SHARPENING A CIRCULAR KNIFE Filed March 14, 1938 2Sheets-Sheet 2 INVENTOR Henry L Ha ell die,

H I5 ATTORNEY Patented July 9, 1940 iiNi'iE STES MEANS FOR SHARPENING ACIRCULAR,

KNIFE Application March 14,

2 Claims.

This invention relates to mechanism for sharpening a circular knife,particularly while the knife is in the course of an actual cuttingoperation.

Circular knives are employed in industry for 5" cutting'a variety ofmaterials. Many of the materials require constant maintenance of anexceptionally keen edge on the knife during the entire cuttingoperation. When the operation is of extended duration, as in thecuttingof a continuous length of material from a block of the material,maintenance of the knife edge at the required degree of keenness forefficiency of cut is a dii'ficult problem. I

In the latter instance, if the block of material operated upon isrubber, as is the case in the disclosures of United States Patents Nos.2,064,508, 2,121,062, granted December 15, 1936, and June 21, 1938,respectively, to Enrique Vincke, an especially difiicult cutting problemis presented. An extremely thin continuous rubber strip must be cut withmicrometric nicety and without flutes from the circumferential surfaceof a rotating disk of rubber. .Since rubber isa particularly diiiicultmaterial to out under any circumstances, it follows that specialattention must be accorded the factor of knife sharpening.

The present invention has, therefore, as a primary object, the provisionof and means for sharpening a circular knife continuously during itscutting operation in such manner that a super-keenness of knife cuttingedge will be constantly maintained.

An outstanding feature of the invention is the operative relationship ofthe planes and axes of rotation of the circular knife and of acircumferential grinding surface, which is made to rotate against acircumferential blade surface of the knife, while holding the axis ofrotation of the grinding surface fixed relative to the knife.

The planes of rotation of the circular knife and of the circumferentialgrinding surface are perpendicularly related to their respective axes ofrotation, and the latter are so disposed with respect to each other thatone deviates at but a small angle, if at all, from a single plane passedthrough the other parallel with its extension. This insures grindingalong the circumferential blade surface of the knife, or at only a smallangle thereto, thus precluding or greatly minimizing knife vibration. I

In addition, provision is made for honing the other blade surface of theknife to remove the wire edge raised in the grinding operation. Toprevent scoring of the particular bladesurface concerned, and forachieving enhanced smooth- 1938, Serial 'No. 195,595

ness of the ground surface, it is advantageous that the circumferentialgrinding surface be made to oscillate along its axis of rotation duringthe grinding operation. i

While the invention has been perfected and is here set forthprimarilyfor use in connection with the production of rubber threads as:de-,

scribed in the above referred to U. S. patents, its adaptation to thecutting of materials other than rubber is contemplated.

Further features and objects of the invention will be apparent from thefollowing detailed description. Y i

In the drawings: Y i

Fig. 1 represents a top plan view of a circular knife together withsharpening mechanism pursuant to one embodiment of this invention,arranged for a continuous cutting operation.

Fig. 2 represents a-front elevation of-the structure of Fig. '1.

Fig. 3 represents an enlarged fragmentary view, partly in. verticalsection taken on the line 3-4, Fig. 1. 1

Referring to the drawings: The invention is illustrated as applied to amachine for cutting a continuous strip from a rotating-disk of material.Only that structure of the machine per se which is sufficient toindicate the relationships important in the practice of the presentmethod, is illustrated. The machine as awhole may take the form of thatillustrated and described in the U. s. Patent No. 2,121,062 of EnriqueVincke,

In the present illustration, a circular knife 10 is secured on a shaftI! for rotation therewith relative to a disk of cuttable material I2,which in turn, is secured to a shaft'li for rotation therewith. The diskI2 is suitably mounted for rotation and for progressive approximatelytangential feed of its circumferential surface into the cutting plane ofcircular knife Hi. It is to be understood that the respective rotations.of the circular knife 80 and of the disk l2, and the progressive feed ofdisk [2 into the cutting Zone of circular knife l0 aresuitablycorrelated to effect the cuttingof a thin continuous strip of materialfrom the circumferential surface of the disk 12. I

In the cases of the disclosures of the afore mentioned U. S. PatentsNos. 2,064,508 and 2,121,062, the disk IZ'is made up of rubber and thecontinuous strip cut therefrom is extremely thin, and, for practicalpurposes, must be. without flutes and other irregularities. According1y, to derive full advantage from the method and cutting edge of thecircular knife be maintained in a constant state of super-keenness.

Asillustrated, the particular type of circular knife preferably, but notnecessarily employed has a plane surface 10a. and a circumferentialblade surface lllb which intersects the plane surface lfla at an acuteangle to provide the cutting edge lOc of the knife. Thus the cuttingedge of the circular knife is defined by the circumferential bladesurface [0b and the circumferential margin of plane surface Illa, thelatter itself forming one blade surface of the knife.

Sharpening means are associated with the circular knife for continuousoperation on the blade surfaces thereof during the cutting operation.The sharpening means may comprise a grinding mechanism, indicatedgenerally at l4, and a hone mechanism indicated generally at Ii.

The grinding mechanism l4 provides a circumferential grinding surfaceadapted for rotation against the circumferential blade surface "lb ofthe knife, and advantageously comprises a grinding wheel 16 rigidlymounted on a shaft l1 for rotation therewith. Shaft H is journaled alongthe greater part of its length in a sleeve I8 provided with a supportingfoot IBa which is mounted for reciprocation in slideway l9a of asupporting frame 19, the latter being, in turn, mounted'on a supportingtable 20 for adjustment in two dimensions relative to the circular knife10. Shaft I I is connected to a motor, indicted diagrammatically at 2|,for rotation thereby.

The grinding wheel I6 is desirably of right cylinder formation having acircumferential grinding surface I60, of a width approximating, andadvantageously slightly greater than, the Width of the circumferentialblade surface lb of the circular knife; thus substantial uniformity ofwear of the circumferential grinding surface 160., and complete grindingcoverage of the blade surface are assured.

It is to be noted that the shaft II on which the circular knife It] ismounted, is perpendicularly related to the plane of rotation of thecircular knife, and that the shaft I! on which grinding wheel I6 ismounted, is perpendicularly related to the plane of rotation of thegrinding wheel. Thus, the plane of rotation of circumferential bladesurface Illb of the circular knife is perpendicularly related to itsaxis of rotation, and the plane of rotation of circumferential grindingsurface l6a is perpendicularly related to its axis of rotation. Theshaft H, i. e., the axis of rotation of circumferential blade surfaceHlb, is, as illustrated, so disposed relative to the shaft I1, i. e.,the axis of rotation of circumferential grinding surface 160,, that asingle plane may be passed through both of the stated shafts, i. e.,axes of rotation, parallel with the lengths thereof. Advantageously, theplane of rotation of grinding surface [6a is made to oscillate along itsaxis of rotation, i. e., the shaft I1, for preventing scoring of theblade surface lb and for achieving smoothness of grind.

While it is usually preferred that the axis of rotation of thecircular'knife and the axis of rotation of the grinding surface beexactly so disposed with respect to each other that a single plane maybe passed through both parallel with the lengths thereof, and while theillustrated embodiment discloses such relationship, it is contemplatedthat-the axis of one might be set at an angle-desirably only a slightangle say 10 degrees or thereabouts, but in no case greater 2,207,433 lif than 45 degrees-to a plane passed through the other parallel with itsextension.

Where there is a definite though small angular relationship, as aboveexplained, provision for oscillating the grinding surface across theblade surface of the knife may be dispensed with, since scoring of theblade surface will be substantially precluded by the slight cross-grind.It is to be noted that the degree of angular relationship must bedetermined for the particular case, since certain assemblies willwithstand the tendency of the cross-grind to produce knife vibrationbetter than other assemblies. Therefore, within the limits set forth themost advantageous disposition of the stated axes with respect to eachother must be determined by the machine and knife construction, the typeof material to be cut, and the degree of thinness of cut desired.

For accomplishing oscillation of grinding surface lGa transversely ofblade surface IOb, the supporting foot l8a of sleeve I8 may be rigidlymounted on a carriage 22 for sliding reciprocation within the confinesof slideway bed [9a.

Supporting frame I9 is configurated to provide the slideway bed [9abetween limitingend members 19b and I90. Carriage 22 fits into theslideway for sliding reciprocation between the respective end members.Desirably centrally located in the end member [9b, and extendingtherethrough, is a threaded plug 23 having a recess 24, whose end opensinto the slideway. A recess 25 is coordinatingly located in the upperend of carriage 22. A coil spring 26 is positioned between carriage 22and end member IS!) with one end in recess 24 and one end in recess 25.The tension in coil spring 26 normally urges carriage 22 toward endmember I of the supporting frame.

Formed desirably centrally in end member I90 is an open-ended cylinder21, into which fits a piston 28 having a head 28a and a rod 28b, thefree end of the rod being secured in a suitably placed bore 29 in thelower end of carriage 22. The piston 28 is adapted for upward actuationwithin cylinder 21 by the pressure of oil or other suitable fluid mediumsupplied to the cylinder through a conduit 30, the latter being securedin a cylinder head 3| threaded to the cylinder 21. Pressure impulses atsuitably timed intervals are transmitted to the piston head 28a throughthe medium of the fluid in conduit 30, the pressure impulses beinginitiated by suitable means such as the motor driven piston-cylinderapparatus indicated generally'at 3|. For obtaining tightness precludingfluid fiow'past piston head 28a in cylinder 21, a cup leather 32 may beemployed.

Fluid pressure impulses suitably timed by the piston-cylinder apparatus3!, and restoring pressure impulses effected by spring 26 accomplishreciprocation of carriage 22 within its slideway bed 19a, and thusoscillation of the plane of rotation of grinding surface I6a along itsaxis of rotation.

For attaining proper angular placement of grinding surface 16a relativeto circumferential blade surface I llb of the circular knife, thegrinding mechanism is preferably mounted for si multaneoustwo-dimensional adjustability in a single plane. Supporting frame [9 iseccentrical- 1y hinged on its supporting table 20,"for pivotal movementin a single plane, through the medium of extending ears l9d, l M whichare journaled on an eccentric crank portion of a shaft 33, the shaftproper extending between and being journaled in upstanding supportingears 20a, 20a, of table 2|].

A slide 34, mounted for sliding reciprocation on a slideway bed 201)provided on table 20 and extending between the upstanding supportingears 29a, 283a, has an upstanding boss 34a articulatively connected toan end of frame is, which is remote from its location of hinge. Thearticulate connection is advantageously had by means of a slotted link35 pivoted at one end to the i3 and adjustably secured at its other endto boss 34a. by the nutted bolt 36 received in the link slot.

Manual adjustability is afforded by a crank 31 having a shank 31a.threaded between an upstanding post 38, which is rigidly secured totable Eli, and boss 34a of slide 34.

Rotation of crank 31 will effect raising or lowcring of grinding surface[6a into or out of contact with knife blade surface [0b in the correctangular relationship.

The exact nature of the eccentricity of shaft 33 relative to thejournaled ears l9d, I9d may be controlled by manually rotating the shaftslightly one direction or the other. A knurled thumbscrew 33-l, Fig. 1,is provided for the purpose.

The supporting table 20 may be adjustably mounted on a base 39,preferably supported independently of the cutting machine.

In the operation of the grinding mechanism relative to its particularblade surface of the circular knife, it is desirable that the grindingsurface rotate against the direction of rotation of the circular knife.

The sharpening operation of circular knife II! is completed by honingknife blade surface Illa, for removing the wire-edge raised by thegrinding of knife blade surface I011. This may be accomplished by theuse of honing mechanism as indicated generally at 15.

A motor 40 is mounted in a bracket 4| extending from a slide 42 mountedfor vertical adjustment in the guide frame 43. An extension 44 of therotor shaft of the motor depends above the blade surface Illa of thecircular knife, and has secured thereto a hone wheel 45. When properdisposition of the hone wheel against knife blade surface Illa has beenaccomplished by adjustment of manually operable crank 46 for control ofvertical reciprocation of slide 42 within its guideway frame, rotationof the rotor shaft of motor 40 accomplishes rotation of the honingsurface of hone wheel against blade surface Illa.

Guideway 43 may be adjustably mounted on the base 39 as for instance, byscrews 41 cooperating with slots 48.

A wiper 50, preferably of resilient material such as rubber, may bemounted adjacent the blade surface margins of the upper plane surface ofthe circular knife for removing lubricant and debris incident to thesharpening operation,

Whereas this invention has been illustrated and described by referenceto specific forms thereof, it will be understood that many changes andmodifications may be made without departing from the spirit of theinvention as set forth herein and in the claims that follow.

I claim:

1. Adjustable grinding mechanism for a cutting blade mounted forsubstantially continuous cutting movement, the cutting blade having ablade surface inclined toward the cutting edge thereof, which comprisesa grinding wheel mounted for rotation relative to said blade surface insuch manner that the circumferential contact surface thereof extendssubstantially longitudinally with said blade surface, rigid supportingmeans independent of the mounting of said cutting blade, a supportingframe eccentrically pivoted adjacent one of its ends to said supportingmeans, the pivotal means being adjustable for varying the degree ofeccentricity thereof, and said grinding Wheel being mounted on saidsupporting frame, carriage means mounted on said supporting means formovement transverse to the oscillating axis of said pivotal means, meansarticulativelyconnecting said supporting frame with said carriage meanswhereby movementof said carriage means eifects a two dimensionaladjustment of said grinding wheel relative to said blade surface, andmotive means for driving said grinding wheel.

2. Adjustable grinding mechanism, for a cutting blade mounted forsubstantially continuous cutting movement, the cutting blade having ablade surface inclined toward the cutting edge thereof, which comprisesa grinding wheel mounted for rotation relative to said blade surface insuch manner that the circumferential contact surface thereof extendssubstantially longitudinally with said bladesurface, rigid supportingmeans independent of the mounting of said cutting blade, a shaftrotatably mounted on said supporting means, said shaft having aneccentric portion, a supporting frame journaled adjacent one end on saideccentric portion of the shaft and carrying the said grinding wheel andits mounting, a slideway formed on said supporting means, a slidemounted for sliding movement back and forth in said slideway, a linkarticulatively connecting said slide with said supporting frame at alocation remote from said end thereof, means for rotating said shaft,means for moving said slide, and motive means for driving said grindingwheel.

HENRY L. HASWELL.

, thus assuring a fresh clean blade surface for entry into thesharpening zone.

